Air heater



FIG. 1 is a front view of the air heater;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The cross-hatching in FIGS. 1, 3, and 4 represents screening and is understood to extend throughout the areas represented. 

The ornamental design for an air heater, as shown and described. 